At present, spraying of crops with herbicides, insecticides and other agricultural chemicals is generally undertaken in one of two ways. First, spraying is generally done before the crop has reached any appreciable height and thus, there is little risk of physical damage in so spraying. Such spraying in effect is spraying the ground and lodging the chemicals therein. Spraying on standing crops is generally undertaken with a crop duster; that is, by spraying from an airplane. In addition to the substantial expense involved in such spraying, such aerial spraying is to a certain extent inefficient because the chemicals must be sprayed in highly concentrated mixtures due to the load limitations of the airplanes. While the turbulence in the crop, induced by the passage of the plane over the field, does assist in promoting full coverage of the spray, that spray in high concentrations is not as effective as the same amount of chemical applied over the same area when more highly diluted.
While spraying of standing crops is known in Europe, it is the object of the present invention to produce a spraying device which is capable of spraying standing crops while minimizing damage to the crops as well as minimizing the number of passes required through the field. It is further an object of this invention to provide a spraying device which is adjustable in height to accommodate varying crop conditions, especially in view of the fact that the presently known sprayers are generally fixed at one height as those sprayers are not intended to be used on standing crops.
It is further an object of this invention to provide a sprayer which may be easily and inexpensively manufactured and yet which may be easily and conveniently operated, particularly in view of the desirably large size.